Hi welcome to HCm I have gone thru your query regarding pain in chest and back after abs exercise. Dear you have not mentioned your Age, Ht., Wt. which do help in prescribing . Though your pain is a matter of concern , but you are your self responsible for that. first day only you had done 100skips and around 2 sets basic crunches exercises as a result you are suffering . Take rest 1-2 days , lemon juice with a glass of warm water in the morning and a level spoon of turmeric powder + a spoon of almond oil with hot milk at bed time . Include all essential nutrients and supplementsfull of antioxidants to boost metabolism massage with hot olive oil will help ease tenced muscles . I would like to suggest you that before starting any hard exercises you have to do some warming up exercises and should gradualy increase workouts . Start from pranaym - deep breathing 10-15 times , increase upto 50 times slowly. Do jogging , walk , yoga and increase speed slowly . It will increase your stamina and strengthen your immunity gradualy and prepare you for hard work and give resistance from diseases . Avoid processed foods carbs , sugar , fried ,fast foods , Tea , coffee ,alcohol and smoking , stress , sleeplessness and Constipation all will produce biochemical and metabolic conditions in your body that will decrease your immunity. So avoiding is definitely the first step in the right direction to detoxing the body, boosting the immune system . Regular check ups from your proffesoinal are recommended . Hope this helps solves your query .Take care .All the best .Get well soon. Don t hesitate to come back in case of any further query .