Porkchop loosing alot of weight after impaction

Question
I have a guinea pig goes by the name porkchop. i estimate to be around 2 years, and recently  had an anal impaction, he passed on his own and since than i noticed he is very skinny compared to normal, by feel of his belly which used to be quite large and weight by holding him  eating his favorite foods like he used to instead he would take them take a nibble drop it  than go hide in his castle. He isn't drinking as much as normal either...he used to drink his entire water bottle in 2 days now half in 2 days? I notice as i am holding him now that i can feel his spinal bone. this worries me greatly as he used to be very "chunky" now seems like he is almost starved...he is my 4 year old sons's pet we got from a friend don't know much about him other than he was a baby when they got him from the pet store as the guy told them. I did some research as to wat breed he is and came up with Abyssinian. Maybe will help in ur answer. Also pulled out my scale to weigh him he is 1 lb 16 oz not sure wat he was before noticed he lost weight. would appreciate any feed back possible...my son is worried about his pork chop. I am going to keep record of his weight and wat he is eating to monitor closely if the weight loss continues.

Answer
1 lb 16 oz is 2 lbs. Are you sure you didn't meant 1 lb 6 oz?  If so you are right, that's not much for a senior pig. Two pounds is fairly normal, but if he showing signs of losing weight and flesh there is something going on.

Be sure to check his teeth that they are not overgrown or out of alignment. That can cause them not to be able to chew, but it shouldn't keep him from drinking. I can't help but wonder if he isn't older than you think. His symptoms including the impaction sound very much like an older pig who is showing signs of age and possibly coming to the end of his time.

It sounds like he really needs to see a vet to see what's going on. Weight loss and loss of appetite is always a red flag. Please take him to your vet. I think that would be better than me trying to guess what might be going on.