You may go for the following test as primary tests
1)CBC
2)
LFT
3)KFT
4)URINE ROUTINE AND MICROSCOPY
5)XRAY CHEST PA VEIW
6)ECG
7)2D ECHO CARDIOGRAPHY
8)USG ABDO PELVIS.
9)CT BRAIN
1 2 3 4 5 are basic and depending upon situation 6 7 8 9 are performed.
Next Steps
I hope starting first 5 will do for you.