Can this be a diverticulitis flare up?

"The pain associated with diverticulitis is constant and severe, rather than intermittent."

Source: NHS-National Health Service, U.K.

Diverticulitis diet

Purpose
Nutrition therapy for diverticulitis is a temporary measure to give your digestive system a chance to rest. Eat small amounts until bleeding and diarrhea subside.

Diet details
Your diet starts with only clear liquids for a few days. Examples of items allowed on a clear liquid diet include:

Broth
Fruit juices without pulp, such as apple juice
Ice chips
Ice pops without bits of fruit or fruit pulp
Gelatin
Water
Tea or coffee without cream
As you start feeling better, your doctor will recommend that you slowly add low-fiber foods. Examples of low-fiber foods include:

Canned or cooked fruits without skin or seeds
Canned or cooked vegetables such as green beans, carrots and potatoes (without the skin)
Eggs, fish and poultry
Refined white bread
Fruit and vegetable juice with no pulp
Low-fiber cereals
Milk, yogurt and cheese
White rice, pasta and noodles
Results
You should feel better within two or three days of starting the diet and antibiotics. If you haven't started feeling better by then, call your doctor. Also contact your doctor if:

You develop a fever
Your abdominal pain is worsening
You're unable to keep clear liquids down
These may indicate a complication that requires hospitalization.

Risks
Nutrition therapy for diverticulitis has few risks. However, continuing a clear liquid diet for more than a few days can lead to weakness and other complications, since it doesn't provide enough of the nutrients your body needs. For this reason, your doctor will want you to transition back to a normal diet that includes foods with fiber as soon as you can tolerate it.

Source: Mayo Clinic