Drainage thru the sinuses is a very common form of elimination and mostly with mucus.
Good to hear your BP is fine and HR also within the normal range.
There is no doubt that vomiting (and especially persistent vomiting) will leave the body feeling extremely emaciated and prostrated and because of the bodies efforts in going thru this elimination crisis.
REST is an absolute MUST at this time.
Strength will return to "normal levels" once the vomiting has ceased.
Also try slightly hotter water to sip as opposed to just warm water. I am sure this will be even more beneficial for your nausea and gas if you still have them.