My cat peed on my bed

[Ruthieann]

Rileigh, our female cat is about 9 months old. We got her 4 months ago. She is very affectionate and friendly, and we had never had any problems with her.
Two weeks ago, Rileigh peed on my bed while I was in it. Her litter is clean and she is litter trained. Yesterday she peed on a chair, and this morning she peed on our bed while I was in it. After she peed in all 3 occations, she began needing the area.
Is this problem ever going to end? How can I stop her from doing this again? Please help me. I am not fond of stinky cat pee.
Than you,
Ruth