UTI and HPTs

Leanne • Leanne, 26. TTC 2nd child with husband. It`s his first! Have a 5 year old boy, Jackson - want to expand the family!
Hi all!
I'm right at the end of my cycle (due tomorrow or Saturday) and for the past week I have been battling a fiercesome UTI that migrated up to my kidneys. I'm on antibiotics (specially requested so they wouldn't affect a potential pregnancy). So far, all that's come up on HPTs are BFNs. My husband tells me that he has found something online that says having a UTI can affect the results of an HPT. I.E. They give you a false negative. 
Has anyone had any experience of this? A UTI masking a pregnancy?
I have nausea, sore boobs, painful back and lethargy, but I can't work out which is UTI, which is antibiotics side effects, and which could be pregnancy!
Thanks.
Leanne 😊