Yeah you just took too much, especially since your tolerance has probably gone down in the last two months. Nausea is an extremely common side effect of opioids, especially in high doses. I can't give you a timeline for when the nausea will go away by itself, suboxone has a very long duration. But I can try and help you get rid of it. Best thing to do would be to take an antihistamine of some sort, since they counteract the nausea of opioids. Do you have anything like diphenhydramine, promethazine or doxylamine succinate around the house? Or are they available over the counter in your country - assuming you're well enough to get to the chemist and one is open in walking distance, or you could have someone pick them up for you?
Failing that, lying down with your feet up above your head is supposed to help nausea - but please don't do this if you're nodding in and out or in danger of passing out or falling asleep. You could vomit while unconscious and choke to death very easily.
I've also read claims that applying pressure between the two tendons on the middle of the inside of your wrist can reduce nausea (they even have armbands that do this to help with car sickness), but I have no idea if there's any scientific evidence behind it. Can't hurt to try though. Google the exact position.
Other than that, I'm out of ideas. Keep yourself awake, keep yourself hydrated, ride it out and keep some antihistamines on hand next time you get high.
Good luck! Been there, done that, it sucks ass.