Are you sure he didn't suggest paracetamol? There's little to choose between the two drugs above, diclofenac is slightly more powerful (ie if it were to upset your asthma it would be worse than ibuprofen), they are both "NSAIDs". Note I said "if" above, they don't always aggravate asthma unless the asthmatic has aspirin/NSAID sensitivity, best not be alarmist.