You should be absolutely fine from a driving point of view.
It's a type of NSAID and in terms of your tendonitis, should help. However, NSAIDs are notorious for their side effects if used long term (although generally in vulnerable groups) - If you're asthmatic, there's a risk of bronchoconstriction, though I wouldn't have thought your GP would have prescribed you this if you are. Other risks include peptic ulcers, bleeding tendencies, and renal problems.... however, short term, in an otherwise healthy person, there's no reason to be concerned.