Bc shot and headaches ?

I’ve been on the shot for almost 3 months and it was my first time on bc ever. I do have seasonal allergies but I’ve been getting bad headaches since I’ve been put on and I’m not dehydrated or I eat healthy and exercise and I take allergy medication when needed. Some days I wake up with a pounding headache or it occurs throughout the day? I don’t know if this is a symptom or allergies but it’s just frustrating having to take aspirin constantly