Help! Pimples around/near mouth

I never imagined that skin disorders could be so frustrating.  When I hit puberty in junior high I had the worst acne ever.  All over my face, neck and back.  It was horrible and embaressing.  I dealt with that for about three years and then started taking a drug called Acutane, which was a six month treatment.  Well, that pretty much destroyed my acne completely, but it left my skin very dry and I have ever since had to use moisturizers on my face after showering.  About a year later, I got an outbreak of canker sores on the back of my throat that hurt like nothing else.  I stopped eating solid food because it hurt so bad.  The doctors told me it was either viral or bacterial, but either way, they didn't have a treatment for it other than a mouth wash to numb the pain.  This lasted about 10 days and went away, but I continued to get these outbreaks about every six months.  After a while, the outbreaks became less severe, but I was also getting canker sores in other places in my mouth like my tongue and the inside of my cheeks near the gum line.  Then that became the norm for a few years.  A few times, I would get a small one right on the inside of my lip.  After a while, I hardly noticed them and usually if I got a canker sore it would go away in a few days and be relatively painless.  

But a few years ago (I am now 27), I began to get small pimples on the outside of my mouth, which I thought were maybe related to the cankers.  It would usually just be a single pimple right on the skin next to my mouth (but not on my lip) and would develop a white head, and then go away within a week or so.  These were mainly just an annoyance, but they also seemed to become more frequent as time went on.  I also noticed that sometimes a thin, red ring would appear around the circumfrence of my mouth, barely noticable but there none-the-less.  Last year, is when the pimples started becoming a problem.  I started getting them more frequently and they were lasting longer.  Instead of every few months, I was getting them every few weeks.  I went to the doctor finally and she thought it was just a pimple, but thought it might be a cold sore too.  So she gave me a prescription for Valtrax and it seemed like maybe it had worked, but then again it may have just gone away on it's own.  I took Valtrax several times after that, but it was hit and miss as to whether it was effective or not.  Then, 5 weeks ago, I started getting a pimple near the corner of my mouth.  Then another, and another, and another... Finally, I had about 5 or 6 pimples near my mouth and chin.  One even cause the tissue near my lip to swell up and then became very red, but never formed a blister or anything - just left a nice scar.  The skin around my nostrils has also gotten a bit red and I've also gotten some similar bumps on my forehead between my eyebrows.  But it's been 5 weeks and it won't go away!  I also feel a mild burning sensation from time to time near the outbreaks.

I've tried everything.  Changed my diet, no sweets, no coffee, no alcohol, yet it still persists.

Does anyone know what this could be??