Try to avoid the can’t help but construction. While it has been around for a while, most grammarians agree that it’s not the most logical construction. It’s considered to be a confused mix of the expressions can but and can’t help. It’s better to use the always correct can’t help —ing construction.

For example, instead of I can’t help but think he wasn’t telling the truth, say I can’t help thinking he wasn’t telling the truth.

Sherry