When I have trouble with thread shreading & have tried other options, I switch to a metallic needle & often times, it works. I also like Titanium needles but I always use a premium needle in my machines. We spend so much $$ on these machines but sometimes try & go on the cheap side for needles, thread etc. Never usually worth it, in the long run. Try a metallic needle, won't hurt to try one. I also make sure my machine is clean, especially in the bobbin area. Lint builds up in there so quickly or some small pieces of thread get caught up in there & causes nothing but headaches.
My sympathies with the loss of your husband. You certainly don't need other problems to add to your stress. Hope things work out & you can get back to some quality sewing.

The bottom thread cutter may need replacement. My service guy sharpens it. Just had same problem on my innovis 4500d now fixed.

It's a combo machine sewing and embroidery and even though it doesn't use the blade when sewing it still chewed the thread untill sharpened or replaced. We also replaced the needle plate because the thread rubbed and frayed

Hold the spool of thread vertical then turn it upside down. Look to see how much of a twist or curl has on the thread when it is about 8 inches off the spool. Now do it the opposite way and see how much of a twist the thread has. Place the thread back on the machine in the direction which had the least twist. This will be the way it was wound on the spool at the factory. Some machines are finicky and need to be done like this. Try adusting your upper and lower tension to get them in balance. Change your needle and hold your thread when starting to sew. Also, a little longer stitch length might help. Good luck.

One more suggestion. Are you by chance using a ruler foot? I found when I used my ruler foot that the thread quide did not keep the thread in the groove or scarf of the needle. I took a small gauge wire ( I took a twister seal and peeled off the paper) and wrapped it around the needle bar and created another thread guide. Now the thread is properly guided into the scarf and now it works like a charm.

do you think you could post a photo? Sounds intriguing.

I was hoping you would get a definitive "for sure" answer, because I am having sort of the same problem. But my machine just won't pick up the bobbin thread when I have the darning foot on. I did knock it out of alignment and when I got it back from the repair shop, it wouldn't FMQ. Getting ready to take it back to be looked at again.

But I was wondering, on yours, if there could be a problem with the spool allowing the thread to advance? Or if it gets hung up? Mine advances so hurky-jerky with the FMQ foot on, it sometimes flops out of place and gets wrapped around something that holds it firm. I know that's not right, either. In the past, I have had thread get caught by a burr on the edge of the spool.
I hope you find out what's causing it, and can correct it.
Oh, and you might check with your quilt shops and machine shops. I bet they know someone local who works on all kinds of machines.