I’m so sorry that you are suffering with Covid the same time as Penny is so poorly. If she is unable to swallow then sadly I think that maybe her body is shutting down. Recently when I had Ralphie PTS he had refused to take a syringe feed or swallow despite my best endeavours. Wiebke’s guide gives more detail about this A Practical and Sensitive Guide to Dying, Terminal Illness and Euthanasia in Guinea Pigs. I am sure that you will keep her comfy. My thoughts are with you xThanks so much for the kind words. I really do appreciate it. It's currently 5 am here and Penny is still with us but I don't think she's swallowing anymore. I'll gently try a bit more, but then let her rest.
As for me, I'm fully vaccinated but COVID is really knocking me out. I'd be in bed nearly all the time if penny wasn't sick. I'm just so exhausted.