Hello,
You are suffering from swollen private area. You are also having 
back pain. You have history of having 
food intolerance. Swelling in the private area commonly occurs due to 
allergic reaction from certain lubes, condom (latex), rough clothing, perfumed soaps, scented detergents, rough sex, 
bacterial vaginosis, yeast infection, cyst (Sebaceous or Bartholin's), etc. You are suggested to avoid the use of latex (condom), perfumed soaps, do not douche, avoid rough sex.
Get clinically examined by an 
OBGYN, if cyst (sebaceous or Bartholin's)  is detected your treating doctor will incise and drain it if required. You will be given antibiotics and antiseptic dressing done (if required). However, get STD tests done if sexually active to be on the safer side, STI's are treated with antivirals. Take care of your hygiene, wear soft cotton underwear, avoid any sexual activity for a couple of days. Get treated. Stay away from stress, anxiety and distress (physical or emotional). Avoid addictions if any.
Take care. Hope I have answered your question. Let me know if I can assist you further.
Regards,
Dr. Nupur K., General & Family Physician