WORRIED at 20 weeks!!!

Earlier today I was sitting in my recliner just relaxing it hasn't been a stressful day ... anyways I suddenly felt a dropping sensation in my stomach and it scared me a lot ! My cervix is extremely low ... like I can feel it with bearly inserting the tip of my finger .... I'm sorry tmi .. but anyways I have had cramping for a few weeks but nothing severe .. and a yellow discharge .. appointment isn't for a few weeks I'm concerned ... my question is during pregnancy at 20 weeks is it normal for my cervix to be this low ???