I felt little sick, i checked my body temp and was 103 f. 5-minutes later my body temp became 98.6. i checked it again several times and all were around 98.5. next day temp was normal but i felt like joint pain. what caused the temp spike to 103?

It could have been a measurement error. Do not be concerned by on out of whack reading with multiple normal readings. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV and Covid vaccines. Wish you good health!

Such a change over a 5 minute period would suggest a fault in the device you used to measure the temperature. I have never seen that degree of change in such a short period in 4 decades of practice. Feeling sick without fever is relatively common in many conditions.