@sandralynn Is the abscess on the inside of his mouth or on the outside cheek area?
It's just my Grace had an abscess on her cheek (outside) & had it marsupualised after a course of Zithromax (antibiotic) to stop the infection coming back. i then had to keep the wound open to flush the hole with Baytril, but carry on giving the Zithromax orally to fight the infection from both directions! She was on Zithromax for about 5-6 weeks & the pus all dried up & she's been about 5 months all clear now.
If the lump is back again this probably means the abscess has closed over & the infection is building inside again.
If you have transport difficulties it may be worth asking your regular vet to prescribe the Zithromax to clear the infection more quickly than the Baytril, or even ask your vet to contact Simon at the Cat & Rabbit clinic to discuss his treatment & the best way forward.
Is Dougal on any painkiller/anti inflammatory (loxicom) at the moment? Any dental work usually seems to be painful, so Dougal may be trying to eat with a sore mouth if he's had dental work done this may contribute to his appetite/eating ability.
Try hand feeding him strands of Hay to help keep his teeth worn down & hopefully blunten any sharp edges that may be left after the filing down of his teeth.
I gave (turquoise packet)
Supreme Science Recovery for Small Animals (£19 inc P&P from viovet, cheapest i could find at the time)
to Grace when she had digestive problems back along & she would wolf it down off of the spoon, (trying to squeeze her head in the egg cup i was mixing it in at one point). this may be easier than syringe feeding if you have mobility problems?
it looks like Debbie the dental/abscess guru has been tagged already, so....

Healing vibes to Dougal. Speedy recovery let us know how he gets on.

xx