I once had a similar problem when we moved into a new (old) off-campus apartment in Boston. We were told it was cleaned and then within 1-2 weeks we had the same bumps and itching you have. We tried using chemical products and even plastic bed coverings and it didn't work. You have to totally change the environment these little nasty things are living in so that they die and won't come back
We eliminated the problem using essential oils sprays that kill the bugs on contact and also by taking baths with essential oils like clove and peppermint and Germ killer and rubbing the oils on ourselves and the affected areas like ankles and back. We got ours at essentialoilsfromplants.com and they sent us out like 2-3 different bottles of pure plant essential oils right away. They worked like crazy and was cheaper than everything else we tried and we use the oils for tons of other stuff too. We could tell that after a few days it was noticeably better and eventually gone. I would email them. Hope this helps.