I am recovering from a neck and back injury, I have a lot of knots and impinged nerves and get dizzy spells. Definately let your MD know about your symptoms they could be related. Have you had an MRI? If you have not, I think that you should talk to your MD about getting one.
I disagree with using a chriopractor. In my opinion, a good physical therapist will help you regain better health. chiropractor will adjust your spine and require you to return several times a week for a very long time (I tried it and wasted alot of time and money) A physical therapist will help the muscle recover and help you by taking the pressure off the nerve caused by the muscle spasms that you are having. A physical therapist will also teach you how to maintain the health of your back and neck. Once you injure those muscles you need to know how to keep them healthy for the rest of your life.
Another option is Trigger point injections (the MD will inject a very fine needle into the muscle spasm to help release it. Sometimes the needles contains an anesthetic such as lidocaine and sometimes the needle is dry) Google the procedure to learn more.
Neuromuscle stimulation is something similiar to TENS it exercises the muscle and can be done at home with a home unit provided by prescription.
Active On muscle rub is a good product for tempory relief of muscle pain and spasm.
If your odd feeling like passing out is related to your back and neck injury, treatment will help.
The muscle spasm could be blocking blood flow when you are in certain position or it could be putting pressure on a nerve. It is important that you let the MD know when and in what position you are in when the symptoms occur.
Please make sure your MD is aware, there is always the possibility that this is not related to your neck and back injury. Other conditions such as anemia and diabetes can cause your symptoms.
Good Luck, Hope you feel better