Thank you for posting your question.
Red spots over the buttocks and
redness near the anal opening suggests that your child has a
rash at the nappy area. This may be due to infrequent changing of diapers(in case not toilet trained), excessive heat/perspiration or some irritant cloth material of the undergarments.
The blood that you mentioned may be due to one of the
boils being broken while wiping.
However it is also important to rule out that your child does not have blood in his stools. For that I suggest you keep a watch on his stools to observe any red or black streaks. If so, get a medical consultation for the same.
For the rash apply any
zinc oxide containing rash cream or simple
calamine lotion. Assure that the area is kept dry and clean and change the undergarments/diaper frequently.
Also, if you find any new lesions on other parts of the body or an increase in the existing rash, consult a doctor immediately.
If you need any more guidance, do write back.