before you try megadosing B5, try a couple things that are less extreme. I found that good old fish oil helps greatly with controlling the oil levels on your face and eventually that helps prevent acne. Just a couple a day probably wont make a difference, I take about 4g's with every large meal, so 12-15g's a day. I guarantee if you take that amount for a month or so, you will start seeing a difference in how oily your face is.
Always get a good dose of antioxidants, they help greatly. 25000 IU of beta carotene, 1000 IU of E, and most importantly 2-10 grams of C daily. Get your E liquid and your C in powdered form. Vitamin C goes a long way toward good skin health, its also responsible for it's elasticity and normal collagen levels.
Gallon + water a day is very key, helps wash away toxins. Try to wash your pillow cases and towels once a week at least, you want clean sleeping gear not oily.
Ditch your regular shampoos/soaps. They have SLS sodium lauryl sulfate which is a harsh industrial detergent. This aggravates your skin and dries it out to extreme levels, which in turn forces your face to make even more oil. Traditional moisturizers are also loaded with chemicals and don't help as well as they could. Same goes for your regular acne medicine, benzoyl peroxide can easily dry your skin and irritate it.
Instead, go the natural route. At any vitamin shoppe or online you can get Dr. Bronner's oil based soaps. These are made entirely from oils (teatree, coconut, hemp) and they clean amazingly well without any chemicals or drying. I myself have considered my skin to be dry my whole life until I switched to oil based soaps and now there is nothing dry about my face/body. I use the Dr.Bronners to wash my face, shower with it, and there is also a shaving gel. Make sure to get the new pump bottle soaps, those are easier to use and not as oily as the original version. Since you have sensitive/acne skin get the "Baby unscented" kind.
http://www.drbronner.com/
I talk about this all the time but coconut oil will help so much with acne! Ive gotten at least 3-5 PMs from people who tried it and it helped them. Get a good unrefined organic tub of coconut oil, eat 2-3 tablespoons by cooking w/ it or adding it to tea. Also use this as your only moisturizer. Just a little bit is enough for your whole face for the whole day, it absorbs very quickly and has tons of healing powers. Thats the only lotion you will ever need. Also, some people say the coconut oil has helped them with stretch marks from lifting.
If you got any questions let me know.