Methotrexate making my PS worse?

I started methotrexate injections a week ago. My ps is widespread on my limbs but only a small ammount on my buttocks and trunk. I have not had a flare-up for a while so its been fairly comfortable to live with (was reluctant to start the drug as I have been on azathioprine for 43 years and that has been brilliant for the arthritis with no noticeable side effects.). After getting a growth on my neck it now is inadvisable to sunbath or have uvb narrowband treatment, hence the reason to try methotrexate. First injection went well, no side effects for the first week and ps stable. I injected the second does after the first week and by the evening my ps flared alarmingly, very red itching and burning pain that I've not suffered in a while. Was awake all night and nearly called 111. I also felt unwell but no temperature. My eyes felt bleary for several hours but that has gone. Was quite concerned as I am taking this drug for my ps. Rang the hospital and was told to persivere and increase the folic acid to 6 days. week. Would really like to know if anyone has had a similar experience because its affected my confidence in this drug. Thank you Alan