In my personal experience the most important thing to do after a 'yucky' diagnosis (after going to the doctor and taking your meds) is to find support resources. I keep saying that the emotional part of you is just as important of the physical side of you and this is yet another example.
First I would ask your doctor for information and then look at the source of the information they give you. For example, at my breast cancer diagnosis I was given a folder of information with resources - including a flyer from the American Cancer Society, and one from a local support organization. Two good places to start. But I was also told about Breastcancer.org which was another great resource.
Second, I would skip Dr Google but would look for information for patients for that ailment. For example, going back to my Rheumatoid Arthritis I found rheumatology.org which is primarily for doctors but also for patients and I found arthritis.org which is more for patients. both provided me good information.
Third, I went back to that other flyer I got from a local support organization at my breast cancer diagnosis. They had support groups! One full of people like me grappling with their cancer diagnosis. What a great place for me to go.
Finally, I found komen.org which had online support groups.... The last piece I needed.
So when you are faced with that yucky diagnosis, work on finding support. Trust me its out there. You just need to find it.
Recently I was told about two young people around 20 who were facing fairly awful cancer diagnoses. They needed help. I quickly recommended a couple of resources for them - primarily Stupidcancer.org. (I love their tag line - we make cancer suck less. If you are offended by that language you are probably too old for them. They primarily work with people from age 15 to 35 or 40.)
It never ceases to amaze me that people with cancer, or something else yucky, try to struggle blindly without any emotional support. Trust me at my second cancer diagnosis, I quickly jumped on the support bandwagon and joined support groups and had a therapist. By the time I was diagnosed with RA and fibromyalgia I already was connected to many support resources.
Trust me your emotions are important....