pet rat losing hair, has a sore near is eye

Question
I have two pet rats (actually, my son does), John and Marco. Anyway, they live together in a 20 gallon fish tank. I have been noticing lately that Marco has thinning hair to the point where his pink skin shows through, and just yesterday we noticed a bloody sore near his eye. The other rat seems not to be losing hair, (although it may require further inspection in order to really determine that).
It sees like there are tiny red spots on Marco's skin, too. They are 1 year old, medium white rats with black heads. Marco has head tilt, too. He was treated with 10 days of injected antibiotics, but never got over the tilt completely. They both eat a mixture of cereals, nuts, yogurt drops and get fresh veggies a few times a week and plenty of spring water. The bedding is not cedar, but I am not positive what it is, someone gave us a bag from when they had their rabbit, it looks like just light colored wood shavings, came in a 3ft paper bale bag of sorts with pictures of small animals on it.

Answer
The sore by his eye sounds like an abscess, and being by his eye is very hard to treat. For an abscess by the eye, I would have to recommend vet care, because there is a risk of damaging the eye, either through trying to treat it or from the infection that caused the abscess.

As to the head tilt, antibiotics would not help that, it is most likely from a stroke.

Just keep an eye on it, make an appointment with a vet ASAP to have the abscess treated and keep and eye on Marcus for possible future strokes which could cause him to become very weak or to lose strength in his hind quarters.

Tami