It could be due to nausea or any number of things.
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	6	nsubj	6:nsubj|9:nsubj	_
2	could	could	AUX	MD	VerbForm=Fin	6	aux	6:aux	_
3	be	be	AUX	VB	VerbForm=Inf	6	cop	6:cop	_
4	due	due	ADP	IN	_	6	case	6:case	_
5	to	to	ADP	IN	_	4	fixed	4:fixed	_
6	nausea	nausea	NOUN	NN	Number=Sing	0	root	0:root	_
7	or	or	CCONJ	CC	_	9	cc	9:cc	_
8	any	any	DET	DT	_	9	det	9:det	_
9	number	number	NOUN	NN	Number=Sing	6	conj	6:conj:or	_
10	of	of	ADP	IN	_	11	case	11:case	_
11	things	thing	NOUN	NNS	Number=Plur	9	nmod	9:nmod:of	SpaceAfter=No
12	.	.	PUNCT	.	_	6	punct	6:punct	_
