Please relax, your risk is practically nil. In hospitals, clinics and even small dispensaries in India, tetanus injections are given with single use disposable syringes and needles that are opened in front of the patient, so reuse is very unlikely.
HIV also does not survive long outside the body and is not transmitted by a properly used injection. Even in the rare case of a needle stick with truly infected blood, the risk is well under 1 percent. If you actually saw the needle being reused from another patient, then it is worth testing: an HIV 4th generation test and HBsAg and anti-HCV at 6 weeks, and repeat HIV at 3 months for final confirmation. Otherwise no testing is needed. Anxiety about this is very common and can itself cause symptoms; please do not keep checking your body for signs. If the worry is not settling, do speak to a doctor. You can consult me on Practo or at Synergy Multispeciality Hospital, Miraj for reassurance and testing if you wish.