1.1 have a terrible headache. I want to visit my doctor.
=> 1.I have a terrible headache so I want to visit my doctor.

2.She felt so tired and sleepy. She couldn't sleep.
=> 2.She felt so tired and sleepy but she couldn'sleep.

3.The patient needs a specia reatment. Her health condition is getting worse.
=> 3.The patient needs a special treatment because her health conditon is getting worse.

4. My mother should have a healthy diet. She needs to do regular exercise, too.
=> 4.My mother should have a healthjy diet and she needs to do regular exercise,too.

5. You need to take some pain-killers. You can visit the doctor if you want.
=> 5.You need to take some pain-killer or you can visit the doctor if you want.