It's getting worse and worse for 3 days

I'm not sure if it's caused by eating. I had a history of measles a few years ago. The recent work is stressful, but everything is normal recently. On October 1, I was tired after driving from Nanjing for 13 hours. I ate a crab and went to bed at night; No problem on October 2. After lunch, there were two crabs (I'm not sure if it was caused by crabs. Crabs are river crabs, not sea crabs); I went out at 4 p.m. on October 2 and wore a new pair of close fitting pants. Then I felt the strange itching of my legs for about half an hour. I thought it was a mosquito bite and scratched all the time. At about 8 o'clock, I felt the strange itching on my belly and arm, and I thought it was also a mosquito; At 12 o'clock that night, I found many small bags similar to mosquito bites on my body (not like photos at this time); When I got up in the morning of October 3, I found that there were red bags in all the flakes of my body. I bought "Loratadine Tablets" and took one, but it didn't get better that day; Similar photo status was found to be aggravated on October 4; On October 5, I went to the hospital. The doctor said that I was looking for measles and dermatitis and prescribed medicine. After taking it at noon, I still feel no improvement in the early morning of October 6, which continues to worsen.