Pet health anxiety

I managed to convince myself that Tigger has stomach cancers and lung cancers - despite the vet not having found anything concerning 2 days ago (nearly three days) when she saw her

Am I just spiralling, or do I have a valid concern?

Stomach cancers cause this morning (its night time here now) Tigger couldn't hold wet food down at her breakfast time, since then she has kept food down

And cancers in her chest cause she's currently asleep and she keeps breathing a bit quick - normally when she breathes fast in her sleep it means she's dreaming cause she twitches as well as if she has a dream-mousie in her sights

i can't settle cause I managed to convince myself she won't make it to christmas, despite the vet having said about 3 days ago that she cannot find anything serious wrong, in her tummy area or her chest area

I'm terrified cancers is going to take her before christmas day

cause Ebony literally got cancers in her chest area and her tummy area and it got to her brain before we realised it wasn't her asthma

Vet has said Tigger does not have asthma though

idk if i'm making any sense now its past midnight and I'm not even in bed cause I can;t stop keeping watch over Tigger in case she stops breathing cause her lung cancers that was in Ebony is going to take Tigger as well, despite the vet cannot find anything unusual in her chest

cause Ebony's cancers took her in 4 days - literally, she went from starting to have breathing trouble to having fits, within 4 days, and being unable to walk in a straight line and becoming mentally unresponsive to any of us

and cause it took Ebony, thats why its going to have Tigger as well cause it just said it will