Your doctor is likely going to diagnose it as exercise-induced headaches. However, a lot of these are misdiagnosed. I've seen a ton of people diagnosed with this who have actually had cervicogenic headaches. These are headaches caused by poor head positioning, tight musculature, range of motion limitations, etc. There are a lot of lifting positions that put the neck in a bad spot if you're not really careful about it. For example, think of the back squat. A lot of the time, people crane their neck upward or let the bar crush their upper thoracic spine, thus causing poor mechanics at the cervical spine. I'd say do some light workouts, but be very aware of your neck position - don't let your head fall forward. Refer to the picture below and don't let your neck do any of these:
If you look at the forward head position, that's where a lot of people go with back squat, let alone 50 reps of back squat. Definitely pursue the doctor thing and ask if he/she thinks it could be cervicogenic. If so, you could ask for a prescription to physical therapy for postural reeducation, some stretching, coordination/stretching exercises, and more. These can be really bothersome and eventually start to effect your daily life if you're not careful about it. It's definitely something to discuss with your physician.