It really depends what you're using SEO for. If you are just hoping that submitting links places will somehow put you to the top in "medical supply", then you'll be spinning your wheels forever. SEO cannot, CANNOT just improve ranks in competitive keywords by leaning on basic strategies.
SEO is not about how many searchers you can get, its best use is to try and improve the quality of the searchers you get so that you get more actual business. Research longer keywords which you believe will likely produce quality clicks. (An example for you might be "discount tongue depressors") and make sure your site has mentions of these. Don't waste time trying to keyword stuff or build links, just make sure your site hits your long tail words without hurting its overall quality.
People will try to tell you SEO is some kind of Voodoo and that if you follow the right dances you can jump up out of nowhere, really its just common sense and making sure that your website is likely to catch the attention of the many people searching for various longer strings.