Yes painful. I fear the proper thing to do is lift the boat off the keel and tidy it all up.
You donīt mention if the keel is actually leaking around the keel bolts, although the water coming back out suggests it might be. The forces on the hull-keel joint are massive, so sealing it all up and holding it water tight is always difficult. Especially at the fore and aft ends where flexible hull meets inflexible keel.
You will need a stronger sealant than Sikaflex.
I read in some magazines that one is supposed to pull a different keel bolt each year to inspect and if needed replace. I had enough difficulties undoing the nuts on the studs, let alone remove the studs from the keel - I think they were cast into the lead in my boats case.