OH NO! Regardless of Vioxx's heart problems, it would make the disease much worse. These anti-inflamatories cut the immune systems attack on the bugs and they proliferate, because of that. In the case of Lyme at that stage the bugs are involved in heart tissue.
"The doctor she first saw is here in Houston"
Lyme is a worldwide disease and being in TX, the moron should know about all the various diseases that she might have had that are made worse by administering such anti-inflamatories. Lyme is definitely present in TX. It's the most common arthropod borne disease. Sudden onset symptoms like this should not be dismissed and the patient given anti-inflamatories.
"Would another blood test show Lyme disease at this late date?"
A good lab would find past exposure. Unless the disease progress to where secondary lesions, meningitis, endocarditis, synovitis, ect., are present, it may not be easy.
" I remember suggesting she see another doctor but that made her angry at me."
Yes, some people trust there docs as if they were all knowing. Few people are familiar with "medicine", so they don't question. They wouldn't understand anyway. Given your description, the MX doc doesn't know either. She should be on antibiotics and have the appropriate tests done by a competent doc.