Deidre,
When it comes to obsessional thoughts, the best thing to do is to try and seperate yourself from the thoughts allowing them to run UNCHALLENGED in the background as if you have two brains. The thoughts are a product of OCD, and not your everyday rational thinking process. OCD and obsessional thoughts get worse when you challenge them, try to solve them, try to understand them, or ruminate about them. In my experience, even checking in your mind if they are still there sometimes brings them back. I know this is not easy, trust me I know, but it does work over time and with practice.
Realize also that success in dealing with pure obsessional thoughts are not instant. It takes time. Days, weeks, even months. However, the worst thing to do is question or challenge them, this only makes things worse. Also realize, you can obsess over anything, and I mean anything. The hardest thing I have had problems with has been having insight into when I have been obsessing and when I am just normal problem solving, however this is my advice, " If you have having doubts about something (In the absence of concrete reason to have doubts, normally you either: know, don't know, or are unsure and look for information), are searching for certainty, wanting to find perfection, not feeling good enough and looking for the perfect or best way to be good enough, wanting to avoid rejection or hurt, avoiding doing things", then those thoughts and actions are OCD related. Having uncertainty associated with anxiety is OCD.
Also check out: ocfoundation.org & ocdonline.com (articles by Steven Phillipson)
I hope this was of some help,
James