tummy sinus red bumps and low grade fever

My 20 month old. She woke up this morning with small and large red bumps, all over her body (except her scalp, so we don`t think it`s chicken pox). Her bumps also itch, but they are not festered. She also has a low-grade fever. For the past 1 1/2 weeks or so she was complaining of her stomach hurting (so we thought it was a stomach virus, but she never threw up). At that time she also ran a lowgrade fever. After two days her stomach stopped hurting and her fever went away. Then, she was complaining of sinus trouble, such as a running nose, etc. Then she started feeling better until now. The rest of the house has kinda had all the same symptoms but she is so far the only one with the bumps. Does my family have a disease (such as chicken pox, measles, etc.) or are we suffereing from an allergy, or virus of some sort?