Hello, welcome to the forum. I'm sorry to hear that you're feeling unwell, but I'm glad you've found us. The forum is full of members with lots of hints, tips, advice and support to offer you.
Although a blood test cannot definitively show crohns, it can give a good indication of how your body is doing, how much inflammation you may have and if you're becoming malnourished.
I know it is easier to say than do but try not to worry about this too much yet, for an official diagnosis you'll need some imaging tests such as an MRI and a colonoscopy. This all sounds scary but they will help you on the way to getting a firm diagnosis and a treatment plan. There are lots of good treatment options around now, and many people that have crohns find that they have very full and happy lives, especially during periods of remission. Find a good doctor you can trust, and stick with them, voice your concerns and dont let them give you excuses.
Do look around for information, but be careful, use sites that are reliable such as
www.crohnsandcolitis.org.uk . Remember that some of the information on the internet concerns the most serious cases and probably wont apply to you, some of it is out dated and may not include newer, more successful treatments. If you have any questions or worries about anything you see please feel free to come here and voice them, someone will always be able to point you in the right direction.
When you have abdominal pain, heat should help, try using heating packs or pads and take hot baths/showers. Your GI can give you something for diarrhea for the short term while you're getting diagnosed. Ginger and peppermint are good for nausea and should help settle your stomach.
Some people find that some foods will affect the symptoms they have more than others. Try keeping a diary of what you eat and drink, and the severity of your symptoms to see if this applies to you, if it does you'll be able to see what you need to reduce or eliminate in order to ease your symptoms.