I used to work in a dental environment for a few years. Better touching base with your cancer team. Last thing you want is a tooth infection. Plus, ibuprofen does absolutely nothing for infections, and are merely to help with pain. Even antibiotics are rather poor at dealing with tooth infections because when a tooth is infected, it has no blood supply, and for antibiotics to work they need a blood supply to take them to the source of infection. Antibiotics simply help with any infection that has escaped the tooth.

As for what is causing it, could be anything, the list is long. Could be an infection, gum issue, cracked tooth, loose filling, could simply be sensitivity, teeth grinding/clenching or even a nerve issue with the trigeminal nerve that runs through each side of your face etc etc.

If the tooth is sensitive to cold, it can be a benign thing such as sensitivity etc. If it's painful to heat, it's usually indicative of a dying tooth. Those need either root canalled or extracted.

Regardless, dental pain when receiving cancer treatment needs seen to promptly, as do infections. Get an infection ruled out.

Forgot to add, if it happens to be an upper tooth, could be a sinus issue. But still call your team.

Thank you so much for your in depth response! I shall continue to try and contact my team for further advice.