What To Do For The Itching In Various Parts Of The Body?

i got itching on vaious parts of the body for the last 4 months, after itching i got red rashes on the parts of itchng . the skin parts gets heated also. it remains for around an hour or less. after it all the rashes vanish. i got treatment from 2 skin specialists. one gave me allegra120 but it could not works. another gave me tab. xyzal (levocetirizine dihydrocloried) with one zinetac tab which worked. but when i leave to have medicine it again stars itching after 2 days fro the day of leaving the medicine. I am suffering from ankylosing spondylitis also since 7 years. my age is 45yrs. mild constipation is also one of my problem. plz suggest me about my skin desease. regards ravindern kumar new delhi 110022 (m-0000 : 011-0000)