I am not a health professional and could totally wrong, but the itching bumps that resemble pimples remind me of what I recently developed, which is a condition called folliculitis. Several doctors and dermatologists have diagnosed me with this and it is a relatively common condition so I am hesitant to say that this is what you have since your dermatologist was unaware. It is incredibly itchy, and some do not form a head like you said, but mine do not weep/crust over, the only time it has is when it burst from my apple cider vinegar compress so I am not sure. It can be caused by a bacterial, viral or fungal infection and can commonly affect men in the beard area too.
They suspect the one I have is bacterial, so what works for me might not work for you. From forums and personal success, I found raw apple cider vinegar compress to be the best but others have found success with just regular white or apple cider vinegar. I would dilute the solution to 50/50 since it burns, and leave the compress on for 30 mins, you can try up to 1hr. I found it helped ease the itching and inflammation. There are a lot of suggested remedies if you browse Curezone/Earth Clinic specifically for folliculitis.
For carbs you could try to occasionally have pure buckwheat noodles or experiment with coconut flour, teff flour, etc. There’s also zucchini noodles, kelp noodles, shirataki noodles (though I hear they taste like nothing) or you could try cauliflower rice or cauliflower mashed potatoes?
Here’s a link to the safe food list: