acne & doxycycl - how long does this take to work?

I have a red lump on my face below my eye that has been here for about a month. It started out looking like a bug bite and got bigger. It's never really hurt or burned, just more cosmetically bothered me. It doesn't look like what I would consider normal acne. I went to the doctor (just an urgent care dr. not a specialist) a week and a half ago and was told that it was a form of acne. He prescribed 14 days of Doxycycl HYC 100MG twice daily and a topical benzoyl peroxide gel twice a day. I am now on my 11th day of treatment and it doesn't really seem to be much better. From what I've read, it sometimes takes a long time for this antibiotic to work on acne. I'm just wondering if this is normal, or if I should go to a dermatologist to see if it could be something else.

[Dr_Aparna]

Hi,
Doxycycline is a part of the Tetracycline family, which are "bacteriostatic" so it inhibits protein synthesis inside the bacteria.
Besides working as bacteriostatic antimicrobials, it also works as an anti-inflammatory agent. So low doses of Doxycycline can also work for Rosacea or Acne. It targets clinical inflammatory signs of acne, including papules, pustpules, and nodules, as well as non-inflammatory lesions that are consisted of comedos or microcomedos (a thick secretion that plugs a skin duct). However, even in clinical studies, Doxycycline does not work on everybody. It depends on one's genetic disposition and sensitivity to the medication.
It is not recommended for prolonged use or in dosages higher than 20 mg per day, otherwise a bacterial resistance can result, making the bacteria no longer susceptible to the medication.
http://answers.yahoo.com/question/index?qid=20080323233527AAt33zA
You can complete the course of 2 weeks and if it does not subside, consider visiting a dermatologist.
Less commonly, keratosis pilaris lesions appear on the face and may be mistaken for acne.