Need help

At the beginning of last week aka 34 I lost some parts of my mucus plug & have been losing small parts since then I’ve had back aches bh contractions and very bad pressure I’m 35 weeks will b 36 tomorrow and my family is telling me I should start walking or going herbal I’m a little afraid just because once I start walking I find myself cramping & hurting or pain but I know I need to because I don’t want to end up over due any advice? Btw 2nd pregnancy my first pregnancy was full term carried her to 41 weeks

C