Fasting-- is always good for human body but it should be practiced regularly & you should increase fasting duration step by step. As you said it's your 1st time don't try for 3 days. As you are from Pune it's summer season. Body - cells need regular rehydration. Please increase your fasting strength by doing yog -suryanamskar ( compulsory in sunlight with speeking name of Surya/🌞 for best results) breathing exercises - pranayam anulom vilom bhastrika etc. And most importantly dhyaana. As you start with those components , you can feel that you can stay energetic with lower intake of meal.
Detoxification-- you need to be very disciplined to get detoxified. Don't consider it will be like walk on red carpet. You have to give your time to your vaidya. It is best achieved with panchakarma only followed by rasayan or vajikaran chikitsa suggested by vaidya as per your requirement.
Next Steps
For now in lockdown situation regulate your digestion with yog -suryanamskar , pranayam and with proper food . sleep at night and wake up with sunrise.
Remember detoxification is not only for your body. it is for your mind also. So dhyaan , mediation is important.
Health Tips
Follow the rules and regulations in lockdown.
be prepared to help others by keeping you fit physically and mentally