Hello,
Welcome to icliniq.com.
I read your query and understand your concern.
I can suggest only two possibilities for a lady of this young age to have such severe bleeding and pain.
1. Infection - Pelvic inflammatory disease (PID) or vaginal infection, which is transmitted during sex (so the partner is the source), so both have to be treated at a time, or else you will get infected next time of sex. You may have white or yellow or grayish discharge with or without itching, foul smell, pain at the beginning of sex due to dryness (as the lubrication will be reduced), and late towards the end, when a fully erect penis touches the innermost vagina (due to inflammation of the structures around the uterus) pain radiating to the back or thighs. Associated with infection, bowel movement is also affected, a feature of gastritis. Bleeding of periods will be thicker, darker, clots or fleshy masses like, may smell bad, more days with spotting after the periods too. When you have an infection inside the uterus, the blood flow increases as the inner lining is inflamed, and the blood mixed with the inner lining of the uterus forms a thick, doughy or fleshy mass. As the healing of the lining is not complete, it keeps spotting, or you have blood-stained discharge.
There will be throbbing pain even before periods and lasts after periods too. Usually, infection is mixed and not just due to fungus. There will be a family of aerobic and anaerobic bacteria, which cannot be detected on culture. When one is treated and cleared, the other will grow, and if not fully treated, it will regrow. Before treatment, confirm that you are not pregnant. Then, you and your partner can have these medications. Consult your specialist doctor, talk with them, and take medications with their consent.
1. Tablet Fluconazole 150 mg after lunch.
2. Tablet Azithromycin 1 gm one hour before food.
3. Tablet Secnidazole forte after dinner.
All these on the same day for both of you. Later you have capsule Doxycycline 100 mg twice a day for one week, vaginal wash or similar cleanser twice a day, and vaginal pessary capsule Clingen forte (Clindamycin, Clotrimazole, and Tinidazole) or Cansoft CL (Clindamycin and Clotrimazole) once at night for five nights. Your partner can have a local application of any antibiotic and antifungal creams like Candid B (Clotrimazole and Beclometasone) or Candiderma (Beclometasone, Neomycin, and Clotrimazole) on the penis twice a day after washing for seven days. Do not have sex till the infection is fully gone. Do treat it early. Delay may send the infection inwards and may affect future fertility.
2. Any small polyp of fibroids inside the uterus - This will need a simple pelvic scan. Severe pain and bleeding only mean something is disturbing the normal endometrial lining of the uterus.
Hope I have clarified your query, do write back if you have any queries.
Thank you.