Guinea Pigs - bloated

Question
I live in South Africa - Johannesburg.  A month ago I purchased two male guinea pigs.  They are now 3 months old.  I struggled to get proper food and hay, and could only get muesli type food and hay actually meant for rabbits.  I gave them green leave lettuce and carrots, twice a day.  Last weekend a gave them normal head of lettuce you get at your local supermarket.  They go crazy for lettuce.  I think a gave them to much.  Monday night one of them (Charlie) was really bloated.  It went down a bit by Tuesday but did not go away completely.  I took them to my local vet on Thursday who couldn't find anything wrong.  She admitted not being experienced with guinea pigs and advised me to just keep an on them.  Now the other male (Jonty) is also feeling bloated to me.  Both are eating, drinking water, moving around and pooping normally. I tried to cut back on the lettuce, but it doesn't seem to be making a difference.  I was finally able to get proper food through a company in cape town- South Africa.  Its the Burgess line of food.  I purchased Timothy Hay, pellets forage and snacks.  Should I be worried?  Can i change their food over to the Burgess food immediately?   Since they seem to struggle with gas I am unsure what green to give them.  Please any advice would be really helpful.  I am really worried over them

Answer
I'm sorry for your troubles. I know how distressing it can be when your pets become ill.  

The food you had been feeding may have been part of the problem.  Rabbit food is not a proper diet for guinea pigs unless you have some means of replacing Vit C.  Rabbits produce their own Vit C, guinea pigs do not. Therefore, feeding only rabbit food can result in scurvy, a bone disease caused by lack of Vit C.

The other issue with rabbit food is that some manufacturers add antibiotics to the feed. Guinea pigs cannot tolerate the antibiotics as they kill the normal healthy flora in the gut, leaving them open to secondary infections from which they will die.

I'm not familiar with the Burgess line of food, but if it says it's for guinea pigs it should be okay.

One of the ways you can supplement Vit C is by feeding vegetables that are highest in Vit C.  It is always assumed that oranges are the best source, but that is in fact not true.  The best source of Vit C is Kale and/or parsley. They carry the highest amount of Vit C per ounce.

It's not necessary to feed large quantities of lettuce as the water in the lettuce can indeed result in a bloated belly. When traveling with your pigs lettuce is an excellent supplement, as the water bottles often leak in the car making a mess of the bedding. For that reason when we travel to and from shows that are long distance we offer lettuce for hydration.

I hope this helps you out. If you have any other questions please feel free to contact me.