How Long Should Celestamine Be Taken For Allergic Skin Rashes?

im 45 yrs old female 5'5'' in height and 56 kilos..i always have headache sometimes i woke up bec of headache and im having an allergy like hives since i was in diving..its more than 3 months since my last dive and my allergy is on and off.i used lot of creams but it just healed for awhile..now am taking celestamine tablet and it helps to disappear the marks on my skin and itchiness..when should i stop taking celestamine..how many times a day should i take celestamine?