It's a little hard to tell from the photo because we can't get a close-up view of the leaves, but it looks like your plant has tomato leaf miner. See here for a photo that you can use to compare to your plant. If your plant does have miners, this site has some instructions for controlling them. Note that you don't want to drench the area in insecticides, as you will kill beneficial insects that also feed on the miners. An organic alternative to the pesticides listed in the linked site is spinosad.
In the fall, remove ALL tomato leaves and stems from your garden to help reduce fungal diseases and insect infestations next year. Also, you need to rotate your tomatoes (and peppers, egg plants, and potatoes, if you grow them) each year to a different part of vegetable garden; a three-year rotation is usually recommended. This is to reduce diseases (all the plants I listed are in the same family and can therefore get the same diseases).