My bf is 38. has had sharp stabbing pain in left temple 3 dif. times during exertion. lasts <5min. idiopathic stabbing headache? migraine? worse?

Hard question: Based on the extent of provided information, it's really hard to arrive to a definite diagnosis. We'd need to know other symptoms if present, circumstances, whether it was the first episode ever, or it's been recurring over time. Migraines usually last much longer than 5 minutes. Nerve pain can be sharp and usually short lived, so more likely in his case. I'd bet on some nerve irritation.

Exertional headache: The benign primary exertional headache is experienced as a sharp pain for a short duration upon exertion. See an Orofacial Pain or headache specialist to eliminate structural or vascular cause. Indomethacin (25 to 150 mg) is the most commonly used treatment for primary exertional headaches.