=>
1. I have a terrible headache, so I want to visit my doctor.
-> so : vì vậy, vậy nên
2. She felt so tired and sleepy, but she couldn't sleep.
-> but : nhưng
3. The patient needs a special treatment, for her health condition is getting worse.
-> for : vì
4. My mother should have a healthy diet and she needs to do regular exercise, too.
-> and : và
5. You need to take some pain-killers or you can visit the doctor if you want.
-> or : hoặc