Sorry to hear you've had a bad day Essbee. Hope things go better tomorrow.
I give the boys fish oil capsules perfectly up front (not hiding them or anything), and they just swallow them with their juice first thing in the morning. (They learned to take them by practising with jelly sweets.) We've told them they are good for their brains, and they are mostly quite happy to take them.
RE the pasta jar thing, one thing I have noticed with my dss (ds1 in particular) is that the positive rewards do really motivate him (when he's in the mood), but the punishments/negative rewards - e.g. taking a piece of pasta out of the jar - just don't work for him. I don't know why, it simply is not effective in influencing his behaviour. (He does get cross if he loses a piece of pasta, but it doesn't stop the bad behaviour occurring.) So we try and use natural consequences more, and try and get him talking about his feelings, and the situation, and trying to get him to step back and think about what his options are and what might happen, and make wise choices for himself; rather than intervening with punishments.
Essbee, I really feel for you. I am burbling on here, and I don't know if anything I'm saying is at all helpful. My ds1 used to be very volatile at times, and we just couldn't get through to him, but now he is loads better and we rarely reach that 'crisis point'.
Btw is your dd 5? How does she cope with ds?