Could a cyst with an impacted wisdom tooth (upper) ly on nerves and give nerve pain.thankyou?

Yes: When there is a cyst around a wisdom tooth, they both need to be removed asap and sent for pathological evaluation. While rare it could be cancerous and needs to be checked out. Also cyst of that nature tend to continue to grown and cause issues as you have described. See your dentist for a referral to an oral surgeon.

A CBCT would show: A 3-d cone beam ct scan would show the extent of the cyst or granuloma (can't tell the difference without a biopsy), and if there was amy infringement on a nearby nerve.

Remove ASAP: If the cyst is pressing on the nerve, yes it can. But usually this happens on the lower. Please have the tooth removed. The cyst usually comes out with the tooth together. If it is very large, the surgeon/dentist may need to curette it out. Please get this done soon since the cyst may grow larger.