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If you have been having unprotected intercourse (and if you are not on any other form of birth control measures) then chances of pregnancy cannot be ruled out. Your symptoms (changed period pattern, nausea, increased basal body temperature, tiredness, bloating, light cramp, increased appetite) could be suggestive of possibility of pregnancy. Consider visiting your doctor/gynecologist for further examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately). Take adequate rest. Drink plenty of water. Maintain healthy diet.
Take care.