Right side of my body is inflammed. I have tight shoulder, tight lower back, stiff neck just on the right side, tight thighs, etc. What's wrong?

Hard to say. It really hard to say based upon info. For example, what does it mean to say right side of body is inflamed? There are simple things, such as a viral respiratory infection that can be associated with aches in the muscles and joints. There are more serious conditions, such as meningitis, that can cause similar complaints and is life threatening. You should probably be checked. Thank you.
No idea. You need to have a specialist actually examine you.