Hey Kathy,
It could be a couple of things. The first thing I would check is, of course, the tension; sounds like the top tension may be a bit too loose to compensate for the varying weights of the top & bobbin threads.. maybe bump the top tension up a bit. If this does not work, try a bigger needle with a bigger eye. The larger needle shaft will create a larger hole for the thread to settle into, & the larger eye will create less friction on the larger thread. Also, as suggested earlier, you could always wind it into your bobbin, flip it over, & quilt from the back... it's interesting to do it that way at the very least. :lol:
If these suggestions don't work, PM or email me & we'll get it figured out. Then you can post your solution if you want... or keep 'em guessing... :lol: j/k
Let me know how things work out for you.