concerning behavior this morning: standing up on all fours then sitting still on repeat

[Max&Papaya]

My male(?) 2 month old guinea pig stands for two seconds then sits still again, then up again. Any ideas? This is not popcorning behavior. I've never seen my others doing this. It just started this morning. He doesn't seem to be himself today

 

[Piggies&buns]

I’m sorry to hear this.

I’m afraid we cannot know what may be wrong but he may well be in discomfort so please do see a vet today.
Also switch to emergency care - daily weight checks each morning (instead of the routine weekly weight checks) so you can closely monitor hay intake and step in with syringe feeding. Such a young piggy won’t be able to afford to lose weight so it’s important you ensure fibre (hay or syringe feed) intake remains sufficient to keep him stable.

As you also seem unsure as to the sex of the piggy, you can also ask the vet to confirm so you can be certain he is bonded to the correct same sex piggy friend

Emergency and Crisis Care as well as Bridging Care until a Vet Appointment
How to Improvise Feeding Support in an Emergency
Weight and Weight Loss Explained: BMI, Weighing, Poos and Feeding Support Levels
All About Syringe Feeding and Medicating Guinea Pigs with Videos and Pictures

I have also moved your thread to the health section of the forum which is monitored by those of us with designated badges. That way you can ensure specific support and knowledgeable advice

I hope your piggy is ok

 

[Wiebke]

Hi and welcome

This behaviour sounds like pain or irritation but in a spot he cannot reach as it is likely inside his body. Have you had a look at his body and belly where he has any areas that feel sore?

Please switch from weighing once weekly on your normal kitchen scales to weighing daily first thing in the morning for best day to day comparison in order to judge the food intake, with is over three quarters hay and which you cannot judge by eye. Pain is very often an appetite killer. You may need to step in with feeding support at the appropriate level.

The links in the previous post contain all the practical how-to tips and in-depth advice you may need to cover emergency care at home until you can see a vet and medication is kicking in.