KarenJ!

Low platelets, also known as Thrombocytopenia, can be caused by chemotherapy among other things. Here is a link to what the Mayo Clinic has to say on the subject

http://www.mayoclinic.com/health/thrombocytopenia/DS00691/DSECTION=causes

As your husband is so far out of chemo I would look to for drug induced thrombocytopenia as there are over 250 medications that will cause that reaction. If you notice on the Mayo's article some antibiotics will do it as will anticonvulsants both commonly prescribed to OC patients. Neurontin is a popular anticonvulsant many on these forums have been given to ease nerve pain.

Here is another article on drug induced thrombocytopenia that goes into more detail.

http://bloodjournal.hematologylibrary.org/content/116/12/2127.full

definitely read these and keep working with your medical team for answers.

Good luck!

Eric