It will not cost you a fortune go to Chonburi hospital there is a dermatologist there she is one of best in Thailand and because it's a government hospital the prices are good. I saw 4 other doctors who could not tell me what my problem was but she recognised it by looking and confirmed it with a lab test. She speaks good English but it's better to have a Thai with you to get to see her as there is not a lot of English speakers in the hospital. If you go to the multi story car park you will see a 7-11 going into the hospital turn left at the 7 go up the stairs and you are in the right department.