It is quite curious that you could get acne of the scalp but acne rarely causes baldness. If you are experiencing pustules and pimple like formations on the head and the hair is falling off as well, then you just might have a fungal infection of the scalp. Though this quite rare to see in an adult, it is worth exploring as a possibility. The official nomenclature for your condition is tinea capitis or, colloquially, ringworm of the scalp.
Tinea capitis has variant sets of symptoms. This is because the causative organism differs in the cases. Some symptoms manifest themselves as raised papules from the hair shaft that causes the hair to break off eventually from its root. This is characterized by ringworm like symptoms of a raised border inflammation. In yet another variant, the fungus is able to suppress the immune inflammatory response and only cause some patches to develop. Hair loss occurs in this case as well leaving a black spot. The fungus that is responsible for the tinea capitis feeds on keratin in the skin and since hair is completely made up of keratin, this explains the loss of hair. Treating this condition requires only that you get rid of the fungus. Doctors usually use a combination of oral anti-fungals as well as topical antifungal treatments. The condition is rarely serious and once the fungus is eliminated from the scalp, the hair returns.
There is of course also the possibility that your dihydrotestosterone, or DHT, levels are very high. DHT is a male sex hormone that is responsible for hair loss and the fact that you have acne and excessive oil production does corroborate this. There is very little that you can do about DHT levels in your body but what you can do to avoid further loss is to increase your intake of vitamin E and biotin. Both of these vitamins strengthen the hair. Further, it is also a good idea to apply salicylic acid to your scalp to reduce the amount of acne that you face in the scalp. This works by removing dead scalp skin cells allowing for natural skin oils to flow freely and not clog up. To reduce the possibility of ringworm being the problematic factor, shampoo your hair with an antidandruff shampoo that contains either of the active ingredients, zinc pyrithione or selenium sulfide. Also, apply some tea tree oil to the areas of the scalp where you have lost hair from.