I can't believe your doc recommended petroleum jelly. Your skin cannot breath breathe with that stuff on! Whatever you get, be sure it says noncomedogenic which means it won't clog pores and such. If nothing else, try Eucerin.
Try claritin during the day? It's not supposed to make you drowsy.
I agree, though, if it is that bad, a dermatologist will be your best bet. We've had similar with Morgan, when he was a baby he had bad eczema and had to have a prescription, as well as go to an allergist.