I am sorry about the loss of your husband.
In response to your question, diarrhea and vomiting can be caused by many different medical conditions. This is not caused by the warm weather. It will be difficult for me to determine the exact underlying cause without a hands-on examination and some testing, I am sorry. But, common causes are dietary indiscretion, ingestion of a foreign body, infections, or even part of a systemic disease, etc. to name a few causes.
In this case, I would recommend a hands-on examination by your family veterinarian, fecal analysis, and blood work as an initial screening test to determine the exact underlying cause. In the meantime, in any case of vomiting or diarrhea, the first thing to do is give the gastrointestinal tract time to rest. This is what you can do:
1- Do not give things like Pepto Bismol or Imodium. Start her on Pepcid AC (famotidine) 10mg 1/4 tablet every 12 hours for the next 2-3 days. You can buy Pepcid AC over the counter in any pharmacy.
2- No food or water for 6-8 hours. Need to give her gastrointestinal tract time to rest.
3- After 6-8 hours offer a small amount of water. Wait half hour, if no vomiting, offer a small amount of rice (50%) and boiled boneless chicken or ground beef (50%) 4-6 times a day. Keep on this diet for several days then wean into regular diet.
4- Follow up with your family veterinarian for a hands on examination.
My goal is to provide you with excellent service - I hope I've provided the information you were seeking, if you feel you have received anything less, please reply back as I am happy to address follow-up questions. Kindly rate me when you are done.