There are numerous causes of jaw pain , for instance, Temporomandibular joint disorder, improper bite , habits such as clenching, bruxism , improperly placed teeth etc.
Looking at your X-ray , yes you can get the upper left wisdom tooth as it doesn't participate in the biting purposes and is vestigial.
Coming to tooth 46, you should get it replaced by a bridge or even more efficient option that is a dental implant as it doesn't have an opposing tooth due to which the upper first molar (16) will eventually supraerupt leading to other severe dental complications.
White thing on your gum most probably would be a bony spicule or particle , which you must get smoothened by the dentist.
Next Steps
Get a thorough examination done by a dentist. It will help the dentist to rule out the exact cause of your pain