Spotting still after Rhogam shot. Nervous 1st Time Mama!

I had a day of light spotting back around 5 and 1/2 weeks pregnant which my doctor said was normal. I’m now 7 and 1/2 weeks and I started spotting brown blood a few days ago so I called the doctor and because I am A- blood she had me come in today to go ahead and get the Rhogam shot. Now it’s a few hours later and I’ve started spotting red blood so I’m freaking out! Has this happened to other negative blood type mamas??? My doctor mentioned I would need the shot anytime I spotted during pregnancy but does that mean I need to go back again tomorrow for another one??