I had filling in top and bottom teeth. I'm having a lot pain in my jaw and can't open my mouth wide. Is this normal?

Your dentist should be able to diagnose and help you with the problem. It could be one of the teeth previously treated. It also sounds very possibly to be a TMJ issue that was aggravated by you having to keep your mouth open during your last fillings. If so, you will need to find a dentist with advanced training with TMD/TMJ.  Good luck.

Your description of a lot of pain in the jaw, could be a result of a number of factors.1) tenderness and limitation of opening - this could be as a result of simply the injection + the site of injection.2) Pain radiating into the jaw causes be the result of the nerve  damage  in the tooth if it has been heavily filled.My advise , give your dentist a call , explain your symptoms in full, attend your  appointmentYou will need to have an radiograph taken on this tooth for further investigation, Your dentist will then be able to diagnose your problem and give you a full treatment plan