Is my receding hairline at 17 normal?

You are very unlikely to get HIV from a barber trimmer. HIV is not spread by inanimate objects like trimmers but through fluids that carry the virus, such as blood. Look for symptoms such as fever or maybe pimples but always keep in mind the probability of this happening is extremely low.

This could be due to Seborrheic dermatitis, due to usage of strong face washes, frequent rubbing of your eyes , make up or due to usage of Retinol

You might have a medical condition named acanthosis nigricans. It can sometimes cause the lower face to be darker than the rest. It's not dangerous but could be a sign of something more serious, like insulin resistance, that is happening inside your body. You can fix this by eating cleaner, being active, and maintaining skin health. Furthermore, consume a lot of water. 

It is crucial if you have a rash on your penis to consult a dermatologist or a doctor who specializes in the urinary tract as soon as possible. It might turn out to be an ingrown hair but you might be prone to a sexually transmitted disease.

Skin darkening is a typical phenomenon; it could be as a result of different causes like solar exposure or genetic condition. Dark skin tends to become discolored. To lighten your skin, try staying away from the sun, using mild skin care products, and eating healthy foods are the right methods. In addition to this, drinking plenty of water and sufficient sleep also help make your skin seem fairer.

Most youngsters need a face cleanup. When you see that your pores are clogged, whether it is blackheads, or pimples, the cause of these things can be either dirt, bacteria, or skin oil production. Aside from that, do not forget to cleanse your face twice a day with a mild oil-free cleanser, to make your face glow and not raise the probability of skin infection, use a face moisturizer and do not keep touching your face.

This could be a clue to some infection. See a dermatologist immediately for an accurate diagnosis and proper treatment. Immediate medical treatment is vital in such situations.
 

If a dog of yours scratches or nips at you and you don't see any signs of bleeding, cuts, or wounds, the risk of rabies is among the lowest. Rabies is mostly an infection through saliva, hence, when there is no open wound, the chances are minimal. Watch out for any strange signs such as a fever, headache, or tingling in the area near the scratch. In the event, you spot something peculiar, it's best to get checked out by a doctor anyway. But for now, you should be just fine. Rinse the wound under running water and lather it with soap to disinfect it.