Raising credit score takes time
Your credit score IS very low. Most chances that you’ll not be approved, or get very low terms. That will make your loan very expensive.
As to raising your credit score – there is no magic pill. Most people fail to understand that credit score is a lot about history, and you can’t fix that overnight.
The only one thing that you can fix immediately is to reduce your credit, so that your credit utilization is below 35%.
Total debt utilization counts for 30% of your FICO score, so reducing it will raise your score.
How ever, as for your judgement and medical bills (are you late on them?), this stuff remain on your credit report for a long time, and while it’s there it lowers your FICO score.
Even if you pay everything off – the negative entries about ever being late remains on your credit report.