chest and neck blemishes

For the past 2 months or so, I have been noticing breakouts (smallish, red spots) on my chest and the sides of my neck.  The spots last a couple of weeks.  I take a shower immediately after any physical activity, and don't put cream or lotion on those areas (only use Clearasil salicylic acid pads sometimes, but they don't help).  I don't have long hair and can't think of anything else that could be externally irritating me.  I had facial acne as a teenager (I am 23) but it hasn't flared up in awhile.  Is it possible that the spots are caused by dairy, (I eat a ton of yogurt) or another food allergy?

[loiloi]

It is not unusual to have acne at age 23. Acne is related to sensitivity to androgens, rather than age. If you have more androgens than your body needs you will have oily skin. Pores become blocked with excess oil and bacteria which feeds off this oil.
If Clearasil is of limited benefit see your doctor for a prescription strength acne gel such as Differin (adapalene 0.1%).
Have you changed your method of birth control recently? Female acne patients may benefit from taking the combined oral contraceptive pill since the oestrogen it contains blocks the action of androgens on the skin. Avoid the depot shot, mini-pill and hormonal IUD, all of which can make acne worse.
Cow's milk may contain hormones so eating soya or non-dairy desserts may be better for you.
Eloise.