I have been using a microdermabrasion peel to get rid of these forehead bumps to no avail. What else can I try? (photo)

Microdermabrasion, in its early days, was described as epidermabrasion, i.e. the kind of exfoliation that you might get from using a Buf Puf, Loofah or even a stiff wash cloth. So, in general, this treatment for most things, except for perhaps giving your skin a bit of a temporary glow and smoothness, is pretty much a waste of time and money. As to the bumps on your forehead, unfortunately, the photo is not of sufficent closeness or clarity to say much. Rather than continuing on a trial and error self-help basis, you would do well to seek consultation and treatment by a board certified aesthetic dermatologist. If these bumps, for example, are deep-seated milia (tiny epidermoid cysts), these can be opened and the contents extruded. Or if they are overgrown oil glands, technically known as sebaceous hyperplasia, they can be flattened using electrodessication. Your best bet is to seek professional care. Best of luck. 

the photo shows mostly your scalp instead of your forehead but microdermabrasion is not a very effective treatment anyway.  see a board certified dermatologist to get on a program to clear this up