guineapig fighting

Question
I have two male guineapigs which ive had for 3 months now. I bought them together from the same petshop as i thought that as they had grown up together their would be less risk of fighting. Up until now there have been no problems whatsoever but they recently contracted mites so i took them to the vet where they each had a jab and some frontline spot on. He also suggested using just shredded paper instead of hay for bedding which i have done.
Since they returned home they are regularly becoming aggressive towards each other and are always chattering and bum waggling at each other and it is apparent that on is very much dominant over the other as he will no longer allow the other near food when he is there, so i have had to resort to giving them two lots of food at different ends of the cage, however they are more than happy to snuggle up to each other in their bed.
Is there anyway i can help them to get on better or understand what brought this aggression on so suddenly,
thanks
Becky

Answer
Becky
The aggression most probably came on due to them just simply becoming adults.
There is really only one way to make two not compatible guinea pigs get on, and it does not always work and therefore could be a waste of money. CASTRATION ! It is the only thing I can think of, there would be no need to get them both done, just the most dominant of the two.
I hope this helped,
Megan!