Baby wakes up with welt on legs,red about 1/2 inch. During the day They turn a yellow color, then ooze and scab. Happened about three times in last month. First two times only one, last week three on same leg. Took her to doctor first time, told us could be bug bite and gave her Benadryl. Cleaned room, sheets, everything, second one about a week later. This time a couple of weeks between. Any suggestions?