A friend of mine had something similar and she found that a gentle, fragrance-free moisturiser like Cetaphil or CeraVe helped calm the sensitivity and reduce that hot feeling. It is worth checking in with your gynae or even your polyclinic doctor before trying anything new though, since some ingredients are not recommended during pregnancy, and they can also confirm if it is melasma or something else that needs a different approach. The aloe vera is a good gentle start in the meantime, just make sure it is the pure kind with no added fragrance.