Impurities

Sitting on a sofa which was messed with urine

Q: My wife is suffering from a serious disorder about purity. This is all due to urine.

If a child has urinated on a sofa and if someone sits there after its dried without being cleaned, will the other person be impure? Does he/she have to change their clothes?

If he/she sits somewhere else with those same clothes, would that place also be impure?

My wofe is really not well because of this and she’s always washing things, beds, clothes. etc. 

Sprinkling water over impurity to purify it

Q: In my pregnancy I've been getting clear or yellow discharge very rugularly.

So sometimes if I'm out and I have slightly more than a Dirham size then I just sprinkle water over it and try to scrape it a bit but it's always wet, not dry. So sometimes I can't wash and change my underwear when I'm out.

Does sprinkling water over suffice?

It worries me because of my wudhu and salaah and it's validity.