My 1.5 yo stray cat has a lump underneath the skin. Which is smaller than marble, easily movable, round shape and firm. Its not soft nor hard. He is not uncomfortable when I touch, mostly purring! And he is energetic, eats, drinks very well, regular pee and poo activity. but He got his injections from between shoulder blades (which I didnt know its not recommended) I asked my regular vet which she said could be a reaction to rabies shot which he had two months ago. I didnt feel okay so I contacted with another vet (which is quite good) and he said could be 3 things. Lipoma, cyst or sarcoma he want me to monitor him and inform him about lumps growth weekly for a month. Even so it wont grow he wants to do blood work to see if his body fighting something. Is it possible to see from blood work if its sarcoma? After blood work if its not good, he wants to remove completely and send it to biopsy. I feel desperate, should I go this path? I am worried that my cat will go throug alot this time. Should I let him stay with lump and just monitor him. I dont want to lose him. I cant stop crying he is a lovely cat I need advice what should I do?