I had a baby 4 months ago and have been getting headaches and migranes almost everyday for the past few months. What could be causing them?

Anything. Your headaches could be coming from tension, dehydration, lack of sleep/poor sleep, skipping meals, stress, eye strain, teeth grinding, sleep apnea/snoring, or chronic sinus problems.
Need more Info. What was the timing of the headaches onset-how soon after delivery.Did you have heavy bleeding or prolonged hard labor, or an epidural ?Have you had any visual chages or problems nursing?There are a number of possibilties for your headaches. You need to see a neurologist. Possible causes are post-spinal headache or low pressure CSF headache which can occur even without having a epidural or spinal.