As she may not be neutered and she has a large lump associated with her mammary gland, there is a concern she may have a mammary cancer.
It is important the lump is assessed and, if concerned, the vet will biopsy it. If it does turn out to be cancerous, it is best to be removed.
Weight loss should always be taken seriously in an older dog has it can indicate an underlying medical issue. However, if she is exercise more than usual and not eating more calories, this could explain it. If she is under-weight, the vet will likely advise some basic testing such as a blood test.
With regards ***** ***** vomiting, a couple of vomits aren't always a concern and could be due to e.g. an infection or having eaten something she shouldn't have.
We would usually advise resting the stomach and then offering a bland dinner such as a half portion of chicken and rice.
Ensure she has plenty of water and that she is up to date with her wormer.
Do also check there aren't any toxins she has access to such as a house plant, human medicine or cleaning product.