Is there need to be concerned about a lump/swelling that continues to appear. No pain. Located under the jaw bone below ear. Fever 99 -100. Tyl not w?

Yes. Get checked. It could be infection but it could be something more serious like a tumor. If there is a mass that persists a few weeks with no symptoms and for no reason, it may need a scan and/or a biopsy. This is especially the case if there is a history of smoking and drinking or skin cancers for this part of the body.