My 2 yr old female cat is acting very strange, she is meowing constantly but also purring and lying down. She has been spayed . Her stomach looks swollen but she is eating.There is a new cat hanging around our garden and wondered if this has upset her or simply she is unwell and I am not spotting this??

If you're worried that she may be sick, then you need to get her to a vet. They'll be able to test for things that we simply cannot diagnose over the Internet.

She could have a growth but I would just say take her to the vet.