Hello,
Without external examination it is very difficult to confirm a diagnosis,but the various possibilities for your symptoms are folliculitis(might only be felt as small lumps in the skin commonly with a hair arising from centre) , pearly penile papules(multiple, small (about 1-3mm) papules running around the circumference of the crown of the glans penis) , Fordyce spots (small (1-5mm) bright red or purple papules that can appear on the penis and usually effect younger men), sweat dermatitis or contact dermatitis(appear as red small lumps with itching or burning) .
I sincerely advise you to consult a dermatologist and get yourself evaluated for these possibilities. Till then, you should keep the area clean, wear lose comfortable clothes to avoid sweating, use a powder to keep the area dry and use calamine lotion at the sites. Oral antihistamine medications would help if the lesions are itchy.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
If you have not had these before, and they appeared after having the sexual encounters, I suggest you go to the doctor to take a swab to rule out any sexually transmiited disease.
You may have Thrush (Candida Albicans). Although with thrush there is sometimes a white discharge or itchy or sore irritation, some men do not get any symptoms at all, but can pass it on to their sexual partners.
If you do not want to see the doctor, you could try Canesten or Canesten H which can be bought from the pharmacist. If you can't purchase that, ask the pharmacist for an antfungal cream. Some pharmacists will also look and diagnose a problem without you seeing the doctor.
In the meantime, until you get this sorted out, do NOT have any unprotected sex.