I too can relate to the vet bills, this has been a doozy of a year for me too. Woodstock has racked up 5k in the last 7 months by himself. Bad tendon injury, lots of laser therapy, ultrasounds, etc, etc. He's darn near drained the rainy day fund :(
I do have sewing ideas for you! I have a friend who makes felt play food for kids, it's super cute stuff & she does really well on it. I got my nephews a pizza kit, the dough, sauce & cheese is sewed on and then it came with a bag of assorted toppings that had velcro backs. She sells them online on a craft website, does a booth at the county fair, local festivals & the flea market some weekends.
What about horse related sewing projects? Halter/bridle bags, saddle covers, lycra hoods, plain under pads for western riders; my wonderful gma made me 6 to put under my wool show blankets, nicer than pre-made & always the perfect size for my blankets (no extra that hangs out & shows underneath) Fleece leg/polo wraps. My grandma is a formally trained seamstress & has always made custom show jackets (wish I'd have learned, I can make curtains & straight skirts...that's about it!) but she always made good extra income doing repairs on halters, patching blankets, etc. Though much of that type of stuff required using a heavy duty serger & leather needles.
Life is like a camera. Focus on what's important, Capture the good times, Develop from the negatives and if things don't work out, Take another shot.