The right side of my head is in pain. Under my eyes, my jaw my ear and it feels like I have a tooth ache. Is this likely to be a sinus infection?

Probably. Assuming you are otherwise healthy, the answer is probably, especially if you have had a recent cold, and/or plane travel. Call your doc. Rx may include something to open nasal passages, something to thin out mucus, something to kill germs.
Possible but. Though you may have a sinus infection, it could be coming from your teeth. It is common for pain from a tooth and/or abcess of the dentition to radiate into the locations you have described. It would be advised to have it checked out by a dentist to see if it has dental origin.
Could be a tooth. It is possible that it is a sinus infection, but another possibility is an infected tooth. See your dentist for an evaluation to see if a tooth is causing the problem.