muscle ache/spasm in my shoulder area

Uh, not to be an alarmist, but visit the ER and rule out a heart attack?

Okay, well, I'm glad it's not a heart attack.  If it's something that comes recurs, then I'd go with gsquaredmom's suggestion of seeing the doctor.  The only home remedy I can think of would be some ibuprofen and heat or ice (whichever makes it feel better).  

Hope you can find some relief-- shoulder pain is some of the worst! 

You can have neck, back and shoulder injuries. You could have soft tissue adhesions. You could have thoracic outlet syndrome.

Did they do xrays after the beating? I would assume they did. It sounds more like a trigger point adhesion. Have you had massage? find a massage therapist that does trigger point deep massage. You can use heat now since it's been so long. Other things you can try are to lay on a tennis ball, and roll it over the area to work the area of spasm/triggerpoint out.

A student beat you up and hit you with a chair? Do you teach special education? This is terrible. I mean OMG awful. 
The car accident can wreck your arm for a long time. My mom and I were hit years ago (30 years ago) and she still has trouble. We were hit 2 years ago and she still has back and hip trouble. That very well could be the source of your pain. I wish they sold Robaxacet with codeine in the US as that would give you some relief for tonight. My local drug store sells something that is stronger than that and it really helps deep muscular pain (called Spasm Halt). It is awesome stuff!

I am so sorry your were assaulted--especially by a student! I once had a work injury claim--my boss insisted that I file, and they wanted me treated and healed immediately. Nobody was honest about long term damage. I'm so sorry you're dealing with that. I hate that you had to deal with that on top of healing from the physical and emotional trauma. 

I also think your numbness and pain is probably coming from your past injuries and probably pinched nerves--which can be from the bones in the spine, neck, shoulder or inflammation in the area. 

I've had a couple of severe accidents and a lot of pinched nerves, weakness, etc. I have ehlers-dahnlos syndrome which makes your ligaments extra loose and causes joints to overstretch. Historically women who had this syndrome had higher survival rates in childbirth, so more and more people are "double jointed" While you might not break a bone when you twist and ankle, the syndrome can also cause weak blood vessels, which can rupture if the joint is manipulated incorrectly, or nerves in the area can be damaged. My doctors have forbidden me to go to the chiropractor of have physical therapy because my type of ehlers-danlos is so severe that I have high risk of blood vessel rupture or nerve damage--especially since my joints can be so hyperextended.

I get a lot of numbness and tingling. I try to change positions, stretch, and rest the area. I *love* my tempurpedic bed with adjustable base. On days when I can't get comfortable on the sofa, I can adjust my bed like a recliner. Dh also put it a nice entertainment center so I can watch TV, movies, and listen to music over bluetooth as well as get on the internet. --I know the beds are expensive, but there are lots of less expensive mattress pads, cushions, etc. Dh and I have latex allergies, and so many of these gel foam items are made from latex, so the Tempurpedic was right for us.

Even with my old injuries, I can definitely tell when the weather is changing by how much more my body hurts. Quick changes in barometric pressure and cold fronts really make me feel bad. I've tried all sorts of muscle relaxers, but none of them work and most cause bad side effects. 

I really wish that when I was still having lots of pain from my injuries when I was a teen that I hadn't ignored the pain and had gotten better treatment. I have a high pain tolerance and just shrugged it all off--I had no idea how bad the long term effects would be.

Hope you've found something to give you a bit of relief by now. This definitely could be related to the previous injuries, you could very easily have exacerbated something without knowing it. Heat is good - heat some rice in an old sock in the microwave for a minute or two if you can - that will give you some good moist heat. Someone mention laying down and rolling over a tennis ball - you can also place two or three in a sock (good use for those mateless socks lol), and place them between you and a wall and move around to get some massaging action. Hope you feel better - the pain is a PITA.

Maybe frozen shoulder developing? No known cause of it but certainly could be aggravated by an injury. Just a thought.