Yes, you can undergo a Keratin hair treatment to help reduce hair fall. Keratin treatments are designed to help strengthen and nourish the hair and reduce breakage. However, it is important to keep in mind that Keratin treatments should not be used as a primary treatment for hair loss. You should speak to your doctor to determine the underlying cause of your hair loss and the best treatment options for you.

Psoriasis can be a bit challenging to treat but various treatments like medications, laser treatments, alternative treatments like homeopathy etc., avoiding triggers that worsen your psoriasis symptoms can prove useful. I suggest talking to your doctor for proper examination of your condition which will help in deciding which is the best treatment for your condition. 

For this type of condition, one should consult a dermatologist. The rash may involve several causes, which include allergic reactions and skin infections. In case you have already had STI testing and treatment, the rash should be diagnosed by a specialist.