If it's worse after using Thread Heaven, stop using Thread Heaven!
I had this issue when I bind quilts. I use Bottom Line because it's very strong, it's fine and sinks just as beautifully into the fabric as silk does, and I can get a wide range of colors when I buy a bobbin donut. I discovered that it does not like Thread Heaven much, I had the same issues with the Bottom Line twisting and knotting quickly. So I quit using Thread Heaven and now I have no problems at all.
I'm not dogging Thread Heaven, I think it's a wonderful product - for some threads.