I am currently on Oratane and it is getting worse is that normal?

I have been on the pill for about 5 weeks now. 5mg is what the derm gave me.. i noticed my skin started to clear up alot during the 3rd week my skin looks much better however now on my 5th week im getting big cystic acne again.. is that normal? or is that a sign its not working anymore? my lips are super dry and i have a bad rash on my arms its super dry skin.