It's not possible that the condom can be stuck in the vagina for more than a few weeks without infection or discharge. Condom is made of an inert material; it doesn't cause any undue reaction
Next time, check after sexual intercourse if the condom is still on. If not, lie down on your bed, facing up, legs apart. Next, insert your fingers into your vagina and feel around for the condom.
I would recommend the following-
1)Consult a gynecologist to do a pelvic examination and check for any signs of infection. She might also perform a trans vaginal ultrasonography to rule out any other foreign body lesions.
2)Take Tab. Mefanimic acid or tab. Tylenol 500 mg to reduce the abdominal cramps.
3)Always use protection while having sexual intercourse and follow safe sexual intercourse as these pustules may be infected with STD.
4)Follow a strict regimen of exercise .Also eat a balanced and healthy diet. This can help in maintaining a good perinea environment and prevent the chances of such pustules.
5)If the condom is too far up to reach, inject water inside your vagina .Just make sure the water is warm and the device is sterile. This helps the condom move lower in your vagina, enabling you to pull it out.