guinea pig noise

Question
i was recently having my guinea pig sit on my lap as I was petting him as usual-soft stroking, which he normally responds to with a purr like noise. he then squeaked, and so I stopped touching him for a second. All of a sudden, he started screaming, emitting this loud, high pitched noise. My brother brought our other guinea pig over and the guinea pig who was screaming stopped and was quiet. I don't know why he was screaming, because I wasn't even petting him at the time. Could you please help?  

Answer
Hi Sarah

Its quite hard to say what (if anything) might be wrong. However, I would like you to consider 3 things.

1) Please check your pig's skin. My first thought is that even though he started screaming after you stopped stroking him, if he has mites or another discomfort, this could be the reason.

2) Perhaps he was mssing his friend and that is why he stopped when the other pig was brought to him.

3) Is it possible that there was any noise, sudden movement that could have scared him?

I hope that gives you a few ideas but if you think of anything else that is relevant, please do let me know.

Andy