Bring Old Bay and 8 cups water to a boil in a 4-qt. saucepan; add shrimp, reduce heat to low, and cook until shrimp are pink, about 2 minutes. Drain and transfer to bowl.
Add red onions, parsley and dill to shrimp bowl.
In a separate mixing bowl, add apple cider vinegar, lime juice, Melinda's Scotch Bonnet sauce, garlic, salt, and pepper. Slowly wisk in olive oil until dressing becomes a homogenous mixture.
Add dressing to shrimp mixture. Toss well.
Place pickled shrimp in 1 quart glass, cover with lid, and chill overnight before serving.