Hello my friend,
I understand your concern and I will do everything I can to help you. It is not very common for the herpes virus to spread on to the chest, but it can happen. When this happens its known as herpes zoster or (shingles). Its basically caused by the same virus which causes chickenpox. I will include a picture from the net which shows what a herpes zoster rash on the chest looks like. This can help you to determine whether it is from herpes zoster or not. A doctor would need to examine and treat you for this.
However the more likely result of a rash in the summer can be due to sweating. Sweating can contribute to very bothersome heat rashes. They can stay for weeks or even months if not treated correctly. Heat rashes can also persist and get worse. They are basically red or pinkish rashes which develop from the sweat ducts becoming blocked and swelling. This also leads to itching and discomfort. It affects adults in humid climates and babies are especially vulnerable to heat rashes. The rash will only get worse with scratching.
The best way to treat a heat rash is to keep yourself cool and wear breathable clothing. If your able to don't wear an girdles or tight under garments. Cool the affected area with cold wash cloths or a cool bath. Always let the skin air dry rather than using towels. Calamine lotion has been known to help heat rashes. If these measures don't work then I recommend you go the dermatologist. A dermatologist can also treat this type of rash with an ultraviolet light to un block the pores and open up the sweat glands. The rash can also be from an allergic reaction or other skin condition. If it continues to get worse there is a chance of an infection. Be sure to watch it carefully.
I hope this helps. Please click on accept otherwise please request more information. I am always here for you.