This site (and its UC Davis so reliable)
lists plumeria as a 4 which means
"Dermatitis: The juice, sap, or thorns of these plants may cause a skin rash or irritation. Wash the affected area of skin with soap and water as soon as possible after contact. The rashes may be very serious and painful. Call the Poison Control Center or your doctor if symptoms appear following contact with the plants. "
So it is likely the sap caused some irritation to the digestive tract which resulted in the vomiting to get rid of it.
You may want to see if he will drink something for you to help sooth any irritation from the plant fluids or the vomiting. You might try a half cup of milk but be aware that can be a mild laxative too.
Just in case and for future reference, as cash flow is an issue, check with your local humane society to see if there is local low cost vet care, ask your vet if you can do time payments or here are some groups that might help you afford the vet bills:American Animal Hospital Associationhttp://www.aahahelpingpets.org/" Through the AAHA Helping Pets Fund, veterinary care is possible for sick or injured pets even if they have been abandoned or if their owner is experiencing financial hardship."Angels 4 Animalshttp://www.angels4animals.org/"Our services range from financial aid to complete treatmentto those pets and pet owners in need."Care Credithttp://www.carecredit.com/A credit card company for health care, including veterinary care."With a comprehensive range of plan options, fortreatment or procedure fees from $1 to over $25,000, we offer a planand a low monthly payment to fit comfortably into almost everybudget." They have a zero interest program if you pay within a certain time frame and they list the vets who work with their product.God's Creatures Ministryhttp://www.all-creatures.org/gcm/help-cf.html"This fund helps pay for veterinarian bills for those who need help."Help-A-Pethttp://www.help-a-pet.org/home.html http://www.help-a-pet.org/"Our efforts focus on serving the elderly, the disabled, and theworking poor."IMOMhttp://www.imom.org/"We are dedicated to insure that nocompanion animal has to be euthanized simply because their caretakeris financially challenged."The Pet Fundhttp://thepetfund.com/"The Pet Fund is a registered 501(c)3 nonprofit association thatprovides financial assistance to owners of domestic animals who needurgent veterinary care."United Animal Nationshttp://www.uan.org/lifeline/index.html"The m ission of LifeLine is to help homeless or recently rescuedanimals suffering from life-threatening conditions that requirespecific and immediate emergency veterinary care. We strive to serveGood Samaritans and rescue groups who take in sick or injuredanimals. In certain cases, LifeLine can also assist senior citizensand low-income families pay for immediate emergency veterinary care." They also keep a list of local and national help resources herehttp://www.uan.org/index.cfm?navid=163
He seems like he is hungry and thirsty. Should I give him food and water and just monitor him or do you think it is necessary to take him to the vet? Thank you very much
You can give him his dinner if he is interested but if he is still irritated he may vomit again. I'd let him have water and maybe 1/3 of his dinner and if he holds that down for a half hour or so then give him the rest of it.
If he becomes really ill seeming then see the vet but with him vomiting it up and it mostly being an irritant it sounds like he should be OK.
If he is relucant to eat dry food you might give him canned food for a meal or two or soften the dry food with broth.