Hi, welcome to the forum, strong possibility is Atopic dermatitis which is seen due to allergic background and Contact dermatitis due to direct skin exposure to a substance which can be a allergen or irritant.
There is also possibility of Chigger bites which can also cause vesicular lesions which are painless initially but later they can manifest as cutaneous reactions and are associated with itching.
You need to give history of any outdoor activity and tape stripping followed by visualization with microscopy will help to establish the diagnosis.
Vigorous cleansing with soap and water should be done. Clothing should be washed in hot water or treated with pyrethroid insecticides to kill mites.
Even photo drug eruptions can have similar finding. It is seen secondary to any drugs like certain analgesics and antibiotics are known to sensitize the skin to sunlight.
Anti-histamines with appropriate steroids against prescription will help to alleviate the condition. Identify and avoid the triggering factor which you been exposed to recently. Consult a dermatologist. Take care and regards.
Photosensitivity is a real condition that is kind of like what you describe. You should discus this with your dr and see if any medications, supplements or beauty products you use can cause this.