I can sympathize with you, although I'm not a doctor and have no quick fix remedy :( I just wanted to share with you my experience. About two years ago I developed a rash around my mouth and for the life of me could not figure out why. I eventually went to the doctor, and she said it was my Chapstick. I thought she was crazy because I've been using the Chapstick with the black label for years, and this had never happened, but then realized when I ran out I started using two other brands in the interim. My doctor said to stop using any kind of lip anything for a whole week, and no licking my lips! told her I would die if I couldn't put anything on my lips because they are so dry (I'm the girl you see around town with a chapstick on her keychain, applying it every 15 minutes) and she assured me I wouldn't. I took her advice, and even though it was really hard to do, I made it through it. She said to reintroduce the lip brands one at a time, and I narrowed it down to either the new Burt's Bee's stuff or the Carmex I had been using. Thankfully it wasn't my trustee Chapstick. LOL Anyway, you're probably wondering why I'm telling you this, since yours is clearly pregnancy related, but I just wanted to share. I had forgot about the other two lip products I was using, because they were a temporary fix but thought about it later. I'm not saying this would be your situation, but I feel like any and all information can't hurt! Good luck with that!
P.S. I was interested to read what the other mom's thought, and noticed that one mom suggested petroleum jelly. You are free to do as you please, of course, but thought I'd share another interesting piece of information. When I was in dental school, one thing I learned really amazed me. Petroleum jelly (Vaseline, etc..) is not water soluble. Therefore, while it protects the skin, and acts as a barrier, it is also a breeding ground for germs, microorganisms, etc... because they are basically "stuck" and if you are using it on an open sore, or lesion, well, you're asking for trouble. I used to love to use petroleum jelly on things, thinking it was safe, but that section of class really opened my eyes. I know most if not all doctors will agree that using petroleum jelly on an open sore is more harmful than good, and even though you have a rash and might not think you have any lesions, every time you open and then close your mouth, you open tiny little tears into it, not visible to the eye. If you are still skeptical, try this at home: rub some petroleum jelly onto your hands, kind of like lotion. Then run your hands under water. You will notice the water beads up, as it can not penetrate the hands directly. It seems like that would be good, but like I said, mix some germs and bacteria in there, and they’re there to stay. Also, to get it off, you would almost have to virtually scrub your skin raw (or use a good salt or sugar scrub) to get it off of your hands. Doing that to an area of your skin that is already problematic, would cause more irritation, if not tears. Sorry for going on so long about this, I just wanted to express my strong opinion against using the p.j. on anything but un-cracked feet. Thanks for listening, and again, good luck!!