Suggest Treatment For Psoriasis Vulgaris

i m 32 yrs old female.i have psoriasis vulgaris in all my joints for 4 months . also it aggravates in scalp and in some parts of my body .will it manage in applying lotions or i have to take some pills ?i have 2 kids--7 yrs and 1 yr old. it is clinically diagnosed only. would it require proper diagnosis in a hospital like CMC ? What are the diagnostic methods after biopsy ? is it a allergy test..; blood test , or arthritis test ??? i need your great favour regarding this ...