euthanasia/when

My mom has alz and thinks nothing is wrong with her 16 year old cat. About a few months ago I noticed a lump on his back and he became much thinner though he was eating and appeared very active the past few months. I had thought my mother was not feeding him due to her illness even though I am there everyday. When I saw the lump I feared it was bad. I called around to see if I could get help cost wise for the cat but no help. I have had cats my whole life and my gut said leave him be he seemed very content was eating well. To put him through a lot of tests did not seem right. Do not feel it was hyperthyroid.. Months have passed he has gotten thinner and toileting has become an issue sort of. His lumps on his back which I thought were many seemingly are possibly his hind bones with possible lumps?? I freaked as I have been in contact with a vet saying he had many lumps. He felt lumpy as i would pet him to the back. Well I freaked I believe the lumps are on his hind legs or its the boney area above his hind leg. Whatever it is I do not feel he needs to have blood tests to be convinced he should be put down. I know I sound nuts about the lumps and differentiating between bones and lumps which bogles my mind. I am not a stupid person. I guess question is, is it always necessary to do blood tests before putting a cat down?? My gut says no and I feel its time to go to heaven. I will have to sneak the cat out of the house due to my moms illness as she thinks nothing is wrong with him. She had a previous feral which was fed outside for 12 years but lost weight quickly I brought him to the vet saying I feel he needs to be put down. Well he did expensive blood tests it showed he was almost dead and the vet then said I was right in saying the cat should be put down...

Sometimes we should just follow our gut. This cat loves to see me and looks at me as if telling me "you know what to do and when". Being the only caregiver to my mom and now this is so hard knowing on how to handle it.

I have always buried cats here but he will be cremated and I will keep his ashes with me

It isn't necessary to do a blood test, no. I'm not clear on whether the cat has seen a vet at all, though, from your post. There may or may not be something to be done before considering putting the cat down. If it were my decision, I would at least want to have the cat examined and ask a vet's advice.

I know but my gut says he needs to be put down so going to the vet just to get him checked out I doubt will come to that. He will need to be put down that is my fear but I will do what I have to do. Its sooo hard.

I'm so sorry.  I'm glad to hear you're taking him to the vet.  He/she will help you make the best decision for your kitty.