I'm sorry to hear poor Gruber has got this issue; it does sound as if he is very uncomfortable with it all.
By definition, an abscess is an infection so he absolutely needs to be started on antibiotics ASAP. Has he been on two courses of antibiotics for these same abscesses? If so, this is unusual as most will heal with a single course.At this stage, I would advise we take a swab of the infection for culture & sensitivity in case he has a resistant infection. It may also be worth considering exploring the abscesses under sedation/anaesthetic in case there is e.g. a foreign body such as a grass seed inside.
On top of the antibiotics, it sounds as though he will need some anti-inflammatory/pain relief medicine to keep him comfortable.
Abscesses do like to rupture (burst open) and can even do this without the animal interfering at all. This is the body's way of trying to get rid of the pus/infection. In fact, a vital part of treating an abscess is to lance and drain it. We do not close these abscesses with stitches as this would simply trap the infection inside. An exception would be if the defect was especially large. However, even if the skin needed to be closed we would still insert a plastic drain so that the infection could continue to drain.
You did the right thing by using the collar but it sounds as if it is no longer helping. It may be that you need a larger size which he is unable to get into the wound. An alternative would be a soft fabric or an inflatable collar which would not cause further injury. Depending on where the abscesses are, you may also have the option of a body suit. Your local pet store may still be open and may be able to provide these for you.
We do not like to bandage over abscesses as this traps the infection inside and can delay healing.
I would suggest you give it a very good clean with warm salty water now, removing any of the discharge and blood.
It's worth mentioning that your vet is obliged to provide a 24 hour service on week nights so if you feel he is going to be uncomfortable over night, you can request an out of hours visit. This may or may not be at your local clinic but they will certainly be able to tell you where the nearest service is.
It's worth saying that before your appointment (whether today or tomorrow) have him starved in case the vet does need to sedate him as they cannot do this is he has just eaten.