Good morning,
There are countless ways to increase your search engine ranking which I am sure you are already aware but i we would be happy to discuss with you further. In terms of social media, yes it can be a very powerfull tool in reaching current and potential customers.
You mentioned 120 information sheets about various medical conditions. This is probably the point to start.
For the $100 you have asked to bid, we would create groups relating to the conditions linking back to the sheets for more information and your facebook page you have already created. This not only creates followers/fans but opens up discussion about the topics for fellow patient/sufferers to share. There is also the potential to have an "ask the expert" set up in both facebook and twiter where patients can ask questions and have them answered by your client.
I have put an initial 7 days for the project, however this is just for the set up, it would require constant mantanance that could be done by yourself or client.