I do apologize that we seem to be playing time zone tag. Still, I do want to leave my thoughts for your lad’s signs. Especially since his grinding and hunching are red flags of significant pain for Lucky.
First, as you noted, we can see paling of mucous membranes with worms. Still, we can also see it with liver fluke (which Cydectin doesn’t cover). Therefore, it is always best to worm for all parasites +/- check a stool sample to ensure there are no resistant ones lurking that may not respond to what we are using. Otherwise, beyond parasites, we do also need to consider that we can see paling of the gums secondary to internal bleeds (ie due to stomach ulcers --which can present as hunching/grinding but usually black stool too) and possible poor perfusion (if we have gut twists -though this usually doesn't linger for weeks).
That all said, given your further information about his urination and his prayer position (which usually is used to take pressure off the abdominal contents –where the bladder is housed as well), we'd be worried we have a partial urinary blockage +/- urine crystals or stones in the bladder. We can also see bladder tumors, but usually these are in older goats. And while infection is a concern as well, we'd hope that that would have been addressed by the PCN. Therefore, we'd want to consider an ultrasound to see into the bladder and potentially may need his vet to catheterize him to check and remove any urethral blockages.
Overall, these signs to raise a range of concerns. Still, based on what Lucky is telling us, we need to be proactive to address his pain, the secondary issues, as well as look into the bladder/urethra. Depending on their findings, he may just need to be unblocked but if a crystal or stone issue is found, then he may need further treatment (medical but possibly surgical) to address this and prevent recurrence.
Please take care,