Oral sex is NOT a risk for HIV. Human saliva contains enzymes and bacteria that render the virus inactive. (Unable to infect)
Oral sex can put you at risk for other STD's and I would advise posting to our STD Forum for their advice about testing.
Photodermatitis is an abnormal skin reaction to sunlight, or more specifically to ultraviolet (UV) rays. It can be acute (sudden) or chronic (ongoing). Photodermatitis occurs when your immune system reacts to UV rays. You may develop a rash, blisters, or scaly patches.
~ University of Maryland Medical Center
Photodermatitis has nothing to do with HIV or any of the STD's. Follow the treatment plan your dermatologist has prescribed and you'll be fine.
If testing is the only thing that will give you peace of mind, then by all means test. Sure beats living with anxiety.
RW