Follitrax 5 MG for scalp psoriasis.

Hello, i have severe dandruff in my scalp and my doctor prescribed dandruff shampoo like keto az,c win, fungicide etc but it doesn't go away. It will be only in control when i use tarry shine and when i stop it comes back again... Day by day scalp got worser and doctor said that  I Have scalp psoriasis and ordered some blood test and prescribed me with 8 follitrax 5 mg tablet for 1 month only on  Saturday morning and evening and 30 folvite  tablets for a month. When i use folitrax on Saturday i have nausea and vomiting sensation from sunday early morning to afternoon... And when i searched about follitrax on internet i am really very much afraid to take those Medicines as it is used for cancer treatment and it can cause some serious troubles to our body. I am very muuch afraid to take those tablets can some one please help me whether to continue or to stop taking that medicine. And even stopping that Medicine could cause any problems ? Please someone help me.